1. Field of the Invention
The present invention relates to a method for producing a ceramic joined body obtained by joining ceramic sintered bodies to each other.
2. Description of the Related Art
Ceramics has heat resistance, corrosion resistance, and wear resistance higher than those of a metal and a plastic or the like, and can be used under severe conditions such as a high temperature environment and a corrosion environment. Of these, silicon carbide ceramics has excellent characteristics such as high rigidity, high thermal conductivity, and low thermal expansion properties, and is utilized as a high temperature structural member and a member for a semiconductor producing apparatus.
Thus, although the ceramics, particularly the silicon carbide ceramics is a useful material capable of being used in severe environments, it is difficult to make a complicated-shaped member and a large-sized member by the casting of the silicon carbide ceramics. Thus, in making the complicated-shaped member and the large-sized member, comparatively small ceramic sintered bodies, for example, a plurality of block-shaped ceramic sintered bodies are prepared, and the ceramic sintered bodies are joined to each other, to make the complicated-shaped member and the large-sized member.
The following Japanese Patent Laid-Open No. 60-127270 discloses a technique for diffusion-joining ceramic sintered bodies to each other via carbon. Specifically, organic matter is applied onto at least one of joined surfaces of a pair of ceramic sintered bodies. The organic matter is decomposed at a high temperature to form a hard carbon film. The pair of ceramic sintered bodies are heated at a temperature equal to or greater than the degradation temperature of the organic matter in a non-oxidative atmosphere with the joined surfaces of the ceramic sintered bodies brought into contact with each other. In the case of this joining method utilizing carbon diffusion, disadvantageously, it was difficult to uniformly control the whole thickness of a joining layer to a desired thickness.
As a technique for joining a plurality of ceramic sintered bodies to each other, silicon carbide joining for forming a region containing silicon carbide on a joined portion is also performed. For example, in a method described in the following Japanese Patent Laid-Open No. 2005-22905, first, a pair of silicon carbide ceramic sintered bodies are bonded to each other with an organic adhesive to form a preliminary ceramic bonded body. The preliminary ceramic joined body is then heated to 1400° C. or more in an inert gas atmosphere. The heated preliminary ceramic joined body and a joined part on which the organic adhesive is disposed are impregnated with molten silicon, to perform silicon carbide joining.
However, in this case, it is necessary to externally supply molten silicon in order to impregnate the joined part with the molten silicon, which complicates a joining technique. Furthermore, disadvantageously, it was difficult to uniformly dispose the externally added molten silicon in the whole joined part and to homogenize the whole joined part.
The following Japanese Patent Laid-Open No. 03-112871 discloses a technique for reducing the external supply of the molten silicon and performing silicon carbide bonding. In the Japanese Patent Laid-Open No. 03-112871, a silicon carbide ceramic sintered body (sintered body) made by a reaction sintering method and a porous silicon carbide ceramic sintered body (porous sintered body) are superimposed via a binder made of a thermosetting resin containing silicon carbide fine particles. The superimposed product is heat-treated at a temperature at which silicon is molten with sheet-shaped silicon superimposed on the upper surface of the porous sintered body.